阅读说明：本技术 一种牵引车线控制动机构 (Tractor drive-by-wire brake mechanism ) 是由 宋志伟 李晶 杨浩 于 2021-01-30 设计创作，主要内容包括：本发明公开了一种牵引车线控制动机构,包括电动推杆、电动推杆控制器、电动推杆杠杆机构、制动踏板、制动踏板限位开关及角位移编码器。所述电动推杆控制器通过CAN总线接收集成式自动驾驶智能控制器发出的制动指令控制电动推杆的伸长,并经滚轮平面副传递给电动推杆杠杆机构,增加后再由另一组滚轮平面副传递给助力阀的输入轴,模拟脚踩踏板的动作推动助力阀及制动阀形成前后桥的制动压力实现制动,所述电动推杆、电动推杆控制器及电动推杆杠杆机构形成电动推杆机构。本发明的有益效果是：在保留现有行车制动系统的前提下,并设计一套电动机械机构与液压助力阀的活塞顶杆并联,用以推动制动阀活塞。(The invention discloses a tractor line control brake mechanism which comprises an electric push rod, an electric push rod controller, an electric push rod lever mechanism, a brake pedal limit switch and an angular displacement encoder. The electric push rod controller receives a braking instruction sent by the integrated automatic driving intelligent controller through a CAN bus to control the extension of the electric push rod, the braking instruction is transmitted to the electric push rod lever mechanism through the roller plane pair, the braking instruction is transmitted to the input shaft of the power-assisted valve through the other roller plane pair after being increased, the action of treading on the pedal by a foot is simulated to push the power-assisted valve and the brake valve to form the braking pressure of a front axle and a rear axle to realize braking, and the electric push rod, the electric push rod controller and the electric push rod lever mechanism form an electric push rod mechanism. The invention has the beneficial effects that: on the premise of keeping the existing service braking system, an electromechanical mechanism is designed to be connected in parallel with a piston mandril of the hydraulic power-assisted valve to push a brake valve piston.)

1. A wire control brake mechanism of a tractor is characterized by comprising an electric push rod, an electric push rod controller, an electric push rod lever mechanism, a brake pedal limit switch and an angular displacement encoder;

the electric push rod controller receives a braking instruction sent by the integrated automatic driving intelligent controller through a CAN bus to control the extension of the electric push rod, the braking instruction is transmitted to the electric push rod lever mechanism through the roller plane pair, the electric push rod controller is transmitted to an input shaft of the power-assisted valve through the other roller plane pair after the electric push rod controller is increased, the power-assisted valve and the brake valve are pushed by simulating the action of stepping on a pedal to form the braking pressure of a front axle and a rear axle to realize braking, and the electric push rod, the electric push rod controller and the electric push rod lever mechanism form an electric push rod mechanism;

the brake pedal, the brake pedal limit switch and the angular displacement encoder form a brake pedal mechanism;

the output end of the electric push rod mechanism and the rotary baffle end of the brake pedal mechanism simultaneously contact an input roller of the hydraulic power-assisted valve to form a roller plane pair;

the electric push rod mechanism and the brake pedal mechanism and an input shaft roller of the booster valve form a non-fixed connection type roller plane pair, and the electric push rod mechanism and the brake pedal mechanism can freely push the input shaft of the booster valve and do not influence each other.

2. The tractor line control brake mechanism according to claim 1, wherein the electric push rod is provided with an electric push rod linear displacement encoder for reading the displacement of the electric push rod, and the displacement of the power-assisted valve input shaft corresponding to the displacement of the electric push rod is obtained through a mechanical constraint geometric relational expression of the lever mechanism.

3. The tractor brake-by-wire mechanism of claim 1, wherein the electric push rod is maintained in a fully retracted initial position during manual service braking without affecting the spring return of the pedal after being stepped.

4. The tractor brake-by-wire mechanism of claim 1, wherein during automatic drive service braking, the electric push rod extends and pushes the power valve input shaft, and at the same time, the roller of the power valve input shaft is disengaged from the output baffle of the brake pedal, and the brake pedal is maintained in an initial state of being not stepped under the action of the return spring.

5. The tractor brake-by-wire mechanism according to claim 1, wherein a pressure sensor is additionally arranged on each of the front and rear axle service brake hydraulic circuits to detect service brake pressures of the front and rear axles in real time.

Technical Field

The invention relates to the technical field of automobiles, in particular to a wire control brake mechanism of a tractor.

Background

When the existing brake pedal is manually stepped, the two-position four-way valve in the power-assisted valve switches positions, so that the left cavity of the power-assisted oil cylinder is communicated with a steering pump pressure oil path, a power-assisted piston rod and a brake valve piston connected with the power-assisted piston rod are pushed, brake fluid is squeezed, and brake pressure is built on a front axle brake and a rear axle brake. Meanwhile, the steering pump supplies pressure oil to the hydraulic steering gear through a pressure stabilizer oil way of the power-assisted valve, and because the volume of hydraulic oil required by the power-assisted oil cylinder is very small, the hydraulic oil supply of the steering gear oil way cannot be influenced during braking, and the priority problem of braking and steering does not exist.

Disclosure of Invention

The invention aims to provide a tractor drive-by-wire brake mechanism, which is characterized in that on the premise of keeping the conventional service brake system, an electric mechanical mechanism is designed to be connected in parallel with a piston mandril of a hydraulic power-assisted valve so as to push a brake valve piston.

The technical scheme of the invention is realized as follows:

a wire-controlled brake mechanism of a tractor comprises an electric push rod, an electric push rod controller, an electric push rod lever mechanism, a brake pedal limit switch and an angular displacement encoder.

The electric push rod controller receives a braking instruction sent by the integrated automatic driving intelligent controller through a CAN bus to control the extension of the electric push rod, the braking instruction is transmitted to the electric push rod lever mechanism through the roller plane pair, the braking instruction is transmitted to the input shaft of the power-assisted valve through the other roller plane pair after being increased, the action of treading on the pedal by a foot is simulated to push the power-assisted valve and the brake valve to form the braking pressure of a front axle and a rear axle to realize braking, and the electric push rod, the electric push rod controller and the electric push rod lever mechanism form an electric push rod mechanism.

The brake pedal, the brake pedal limit switch and the angular displacement encoder form a brake pedal mechanism.

The output end of the electric push rod mechanism and the rotary baffle end of the brake pedal mechanism simultaneously contact an input roller of the hydraulic power-assisted valve to form a roller plane pair.

The electric push rod mechanism and the brake pedal mechanism and an input shaft roller of the booster valve form a non-fixed connection type roller plane pair, and the electric push rod mechanism and the brake pedal mechanism can freely push the input shaft of the booster valve and do not influence each other.

Furthermore, an electric push rod linear displacement encoder is installed on the electric push rod and used for reading the displacement of the electric push rod, and the displacement of the input shaft of the power assisting valve corresponding to the displacement of the electric push rod is obtained through a mechanical constraint geometric relational expression of the lever mechanism.

Furthermore, when the vehicle is manually driven and braked, the electric push rod can be kept at the initial position of complete contraction, and the spring reset after the pedal is stepped is not influenced.

Further, during automatic driving service braking, the electric push rod extends to push the power assisting valve input shaft, meanwhile, the roller of the power assisting valve input shaft is separated from the output baffle plate of the brake pedal, and the brake pedal is kept in an initial state without being stepped under the action of the return spring.

Furthermore, a pressure sensor is respectively additionally arranged on the front axle driving brake hydraulic circuit and the rear axle driving brake hydraulic circuit so as to detect the driving brake pressure of the front axle and the rear axle in real time.

The invention has the beneficial effects that:

(1) in the state that the automatic braking is not implemented by the automatic driving vehicle, the forced braking is implemented by manual intervention; since the electric push rod is maintained at the initial position of full contraction, the brake pedal is also maintained in the initial state of being not stepped, i.e., the pedal limit switch is maintained in the normally closed state. At the moment, a safe driver manually treads a brake pedal to disconnect the pedal limit switch, the change of the switching value is detected by the Ioput of the VCU and reported back to the upper-layer automatic driving intelligent controller, and the vehicle service brake is manually taken over.

(2) When the automatic driving vehicle enters into the automatic braking state, the manual intervention implements forced braking with larger braking force, the electric push rod extends and pushes the input shaft of the power-assisted valve to generate braking pressure, the manual intervention tramples the brake pedal at the moment, although the pedal limit switch is turned off from the normally closed state, the upper-layer automatic driving intelligent controller continuously executes the automatic driving braking program and keeps the extending position of the electric push rod until the rotating output end of the pedal contacts with the roller of the input shaft of the power-assisted valve, the upper-layer automatic driving intelligent controller can issue a jump-off automatic driving braking instruction, so that the electric push rod rapidly contracts to the complete contraction initial position, and the manual take-over is changed. The purpose of the design is to avoid that the electric push rod contracts too early to cause the input shaft of the booster valve to rebound suddenly, the braking force is reduced, the vehicle deceleration is reduced, and the manual pedal treading can increase the braking force and the deceleration suddenly, so that the uncomfortable ride feeling of vehicle brake pause is generated.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a schematic diagram of a tractor brake-by-wire mechanism.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments.

According to an embodiment of the present invention, a tractor brake-by-wire mechanism is provided.

Referring to fig. 1, the tractor line control brake mechanism according to the embodiment of the invention comprises an electric push rod, an electric push rod controller, an electric push rod lever mechanism, a brake pedal limit switch and an angular displacement encoder.

The electric push rod controller receives a braking instruction sent by the integrated automatic driving intelligent controller through a CAN bus to control the extension of the electric push rod, the braking instruction is transmitted to the electric push rod lever mechanism through the roller plane pair, the braking instruction is transmitted to the input shaft of the power-assisted valve through the other roller plane pair after being increased, the action of treading on the pedal by a foot is simulated to push the power-assisted valve and the brake valve to form the braking pressure of a front axle and a rear axle to realize braking, and the electric push rod, the electric push rod controller and the electric push rod lever mechanism form an electric push rod mechanism.

The brake pedal, the brake pedal limit switch and the angular displacement encoder form a brake pedal mechanism.

The output end of the electric push rod mechanism and the rotary baffle end of the brake pedal mechanism simultaneously contact an input roller of the hydraulic power-assisted valve to form a roller plane pair.

The electric push rod mechanism and the brake pedal mechanism and an input shaft roller of the booster valve form a non-fixed connection type roller plane pair, and the electric push rod mechanism and the brake pedal mechanism can freely push the input shaft of the booster valve and do not influence each other.

Furthermore, an electric push rod linear displacement encoder is installed on the electric push rod and used for reading the displacement of the electric push rod, and the displacement of the input shaft of the power assisting valve corresponding to the displacement of the electric push rod is obtained through a mechanical constraint geometric relational expression of the lever mechanism.

Furthermore, when the vehicle is manually driven and braked, the electric push rod can be kept at the initial position of complete contraction, and the spring reset after the pedal is stepped is not influenced.

Further, during automatic driving service braking, the electric push rod extends to push the power assisting valve input shaft, meanwhile, the roller of the power assisting valve input shaft is separated from the output baffle plate of the brake pedal, and the brake pedal is kept in an initial state without being stepped under the action of the return spring.

Furthermore, a pressure sensor is respectively additionally arranged on the front axle driving brake hydraulic circuit and the rear axle driving brake hydraulic circuit so as to detect the driving brake pressure of the front axle and the rear axle in real time. Through the technical scheme: detecting whether faults such as leakage exist in a service brake oil path or not, and judging whether the expected pressure cannot be reached under the condition that pressure brake can be built or not through pressure feedback; in addition, through service brake pressure feedback, a mathematical model among the vehicle running speed, the load, the service brake pressure and the brake deceleration is established, and a data basis is provided for vehicle state monitoring and preventive maintenance.

During automatic driving, the manual service brake is connected and takes over the following two situations for discussion;

(1) in the state that the automatic braking is not implemented by the automatic driving vehicle, the forced braking is implemented by manual intervention.

(2) The automatically driven vehicle enters an automatic braking state, and forced braking with larger braking force is implemented through manual intervention.

With the case (1), since the electric push rod is held at the initial position of full contraction, the brake pedal is also held in the initial state where it is not depressed, i.e., the pedal limit switch is held in the normally closed state. At the moment, a safe driver manually treads a brake pedal to disconnect the pedal limit switch, the change of the switching value is detected by the Ioput of the VCU and reported back to the upper-layer automatic driving intelligent controller, and the vehicle service brake is manually taken over.

For the condition (2), the electric push rod extends and pushes the input shaft of the power-assisted valve to generate brake pressure, at the moment, manual intervention is performed to tread a brake pedal, although the pedal limit switch is switched off from a normally closed state, the upper-layer automatic driving intelligent controller continuously executes an automatic driving brake program and keeps the extension position of the electric push rod until the rotation output end of the pedal contacts with a roller of the input shaft of the power-assisted valve, the upper-layer automatic driving intelligent controller can issue a jump-off automatic driving brake instruction, so that the electric push rod rapidly contracts to a complete contraction initial position, and a manual take-over is changed. The purpose of the design is to avoid that the electric push rod contracts too early to cause the input shaft of the booster valve to rebound suddenly, the braking force is reduced, the vehicle deceleration is reduced, and the manual pedal treading can increase the braking force and the deceleration suddenly, so that the uncomfortable ride feeling of vehicle brake pause is generated.

Wherein, because the electric putter extension position has definite geometric function relation with helping hand valve input shaft gyro wheel position: the roller position of the input shaft of the power-assisted valve is f (the extending position of the electric push rod); meanwhile, the rotation angle of the brake pedal and the position of the roller of the input shaft of the power assisting valve have a determined geometric function relationship: the position of the assist valve input shaft roller is f (brake pedal angle), and the brake pedal angle corresponding to the extended position of the electric push rod at any time is calculated from a functional relation of the brake pedal angle f (extended position of the electric push rod), and in this case, the rotational displacement amount required for the brake pedal rotation output end to come into contact with the assist valve input shaft roller is also calculated. Through the feedback of the absolute linear position encoder on the electric push rod and the absolute angular displacement encoder on the brake pedal, the VCU can judge whether the rotation output end of the pedal contacts the roller of the input shaft of the power-assisted valve or not, so that the rotation output end of the pedal is reported to the running intelligent controller, the automatic service braking is skipped, and the manual service is used for taking over the braking.

Manual pipe connection judgment is carried out under the condition (1), and only the feedback of the pedal limit switching value is needed; and in case (2), the manual connection pipe judgment is carried out, and besides the pedal limit switching value, the feedback of an absolute linear displacement encoder of the electric push rod and the feedback of an absolute angular displacement encoder of the brake pedal are required.

It should be noted that: for the safety consideration of vehicle braking, when the power, output force and stretching speed of the electric push rod are linear:

(1) the reaction speed of the electric push rod through the mechanism brake is at least equal to or better than the emergency brake reaction speed of a human driver, and the average brake reaction speed of the human driver during waking is 0.3 seconds.

(2) In the event of failure of the steering pump, the power valve cannot provide brake power, at which time the driver can bring the vehicle to a stop by applying the brake pedal to generate the necessary brake pressure; in the same way, the electric push rod can generate a braking pressure which is larger than or equal to the braking pressure which can be achieved by a person stepping on the pedal after being boosted through the lever mechanism under the condition of no hydraulic boosting assistance.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.